1. Field of the Invention
The invention relates to a device for securing stock rails in railway switches comprising a bearing plate for the stock rail, a slide chair for the switch blade and an elongate spring element for holding down the rail foot, which spring element is insertable into a tunnel-shaped recess of the slide chair at a tension insufficient for holding down the rail foot, or without any tension at all, and is braceable relative to the rail foot and the bearing plate by a separate clamping wedge extending transverse to the spring element.
2. Prior Art
A device of the initially defined kind may be taken from Austrian Patent No. 321 345. An essential advantage of the known configuration resides in that driving in of the spring element may be effected without any tension, without having to overcome frictional forces during driving in. A defined spring tension that serves to brace the spring element against the rail foot is applied by the transverse wedge introduced subsequently. Since bracing of the spring element against the foot of the stock rail is not effected during the insertion of the spring element, the spring element can be readily inserted into the recess of the slide chair, wherein the spring element in that known embodiment is supported against the wedge in its central zone while the end facing away from the rail foot bears against the bearing plate.
In the known configuration a substantially plate-shaped spring element was used. Due to the spring element being deflected upon driving in of the transverse wedge, the spring element in such a configuration bears against the bearing plate over a more or less large portion on its side facing away from the rail foot of the stock rail, the bearing site being not precisely defined though. The exactly reproducible application of a defined spring force on the foot of the stock rail is affected by the undefined configuration of the abutment on the bearing plate. It must be initially assumed, in particular, that the transverse wedge driven in to define the spring force is to have but a relatively slight inclination in order to remain self-lockingly and safely in its position. Furthermore, the end position of the inserted transverse wedge is to correspond to the respectively desired application force. A shift of the bearing point of the end of the spring element facing away from the rail foot naturally also entails a variable force absorption of the spring element and a substantially uniform cross-sectional height of the plate-shaped spring element involves a relatively irregular force absorption of the stresses occurring in the spring.